Air quality in urban areas is deteriorating over time with the increased pollutant distribution levels mainly caused due to anthropogenic activities. In addition, these pollutant distribution levels may relate to changing meteorological conditions. However, the relationships were not researched in-depth in the context of Sri Lanka, a country with a significant impact on climate change. The main objective of this study was to provide a broader perspective on the seasonal variation of tiny particles in air (PM2.5 and PM10), nitrogen dioxide (NO₂), carbon monoxide (CO), ozone (O₃), and sulfur dioxide (SO₂) in two urban cities (Colombo and Kandy) in Sri Lanka over 3 years period (2018–2021) and the possible relationships between air pollution and meteorological variables. Results show that all the aforementioned pollutants except O₃ consistently depict two peaks during the day, one in the morning (∼07:00–09:00 local time) and the other in the evening (∼18:00–20:00 local time). These peaks coincided with the traffic jams observed in both cities. The results further revealed that the concentration of all pollutants has significant seasonal variations. Compared to two monsoon seasons, the highest daily average PM2.5 (31.2 μg/m³), PM10 (49.5 μg/m³), NO₂ (18.9 ppb), CO (717.5 ppb), O₃ (18.5 ppb), and SO₂ (9.4 ppb) concentrations in Colombo are recorded during northeast monsoon (NEM) seasons while contrast pattern is observed in Kandy. In addition, it was found that wind speed with its direction is the most influencing factor for the pollutant concentration except for SO₂ and O₃ in two cities, and this is irrespective of the season. This study’s findings contribute to understanding the seasonality of ambient air quality and the relationship between meteorological factors and air pollutants. These findings ultimately lead to designing and implementing season-specific control strategies to achieve air pollution reduction at a regional scale.

中文翻译：

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城市环境中空气污染物的季节性变化及其与气象参数的关系

随着时间的推移，城市地区的空气质量正在恶化，污染物分布水平的增加主要是由于人类活动造成的。此外，这些污染物分布水平可能与不断变化的气象条件有关。然而，在斯里兰卡这个对气候变化具有重大影响的国家的背景下，这些关系并未得到深入研究。本研究的主要目的是为空气中微小颗粒（PM2.5 和 PM10）、二氧化氮 (NO ₂ )、一氧化碳 (CO)、臭氧 (O ₃ ) 和硫的季节性变化提供更广阔的视角二氧化硫（SO ₂) 在斯里兰卡的两个城市（科伦坡和康提）3 年期间（2018-2021）以及空气污染与气象变量之间的可能关系。结果表明，除 O ₃外，上述所有污染物在白天始终呈现两个峰值，一个在早上（当地时间～07:00-09:00），另一个在晚上（当地时间～18:00-20:00）时间）。这些高峰与两个城市观察到的交通拥堵同时发生。结果进一步表明，所有污染物的浓度具有显着的季节性变化。与两个季风季节相比，日均值最高的是PM2.5（31.2  μ g/m ³）、PM10（49.5  μ g/m ³）、NO ₂（18.9 ppb）、CO（717.5 ppb）、O_{在东北季风 (NEM) 季节期间记录了科伦坡的3} (18.5 ppb) 和 SO ₂ (9.4 ppb) 浓度，而在康提观察到对比模式。此外，发现风速及其方向是两个城市除SO ₂和O ₃外污染物浓度的最大影响因素，并且与季节无关。这项研究的发现有助于了解环境空气质量的季节性以及气象因素与空气污染物之间的关系。这些发现最终导致设计和实施特定季节的控制策略，以在区域范围内减少空气污染。